Gaseous repeater in circuits of low impedance.



, H. DE P. ARNOLD. GASEOUS RE'PBATEE IN CIRCUITS OFtLOW IMPEDANCE.

APPLICATION FILED MAY 28, 1914.

Patented Mar- 2, 1 915.

2 SHEETSSIIEET 1.

//7 Men fa /*1 v HdlO/d 0. Arno/d l V/fnes ses:

H. DE P. ARNOLD.

APPLICATION FILED MAY 28, 1914.

GASEOUS REPEATER IN CIRCUITS OP LCW IMPEDANCE.

Patented Mar. 2, 1915.

2 SHBETSSHEET 2.

//7 yen/0r. "rm/d D. Arno/d il/1 v HAROLDIDE FOREST ARNOLD, OF EASTORANGE, NEW JERSEY. ASSIGNOR TO WESTERN ELECTRIC COMPANY, OF NEW YORK,N..Y., A CORPORATION OF ILLINOIS.

GASEOUS REPEATER IN CIRCUITS 0]? LOW IMPEDANCE.

Specification of Letters Patent.

Patented Mar. 2, 11915.

- Application filed May 28, 191a. Serial No. 841,568.

peaters generally, and of vacuum discharge repeaters more particularly,as ampl fiers without transformers;

Still more particularly, it relates to the use of thermionic repeatersfor securlng amplification of current in circuits of low 1mpedance. By athermionic current is meant current discharge from a hot cathode. Ex-

\ amples of thermionic repeaters are the De Forest audion disclosed inPatent No. 870,532,'date'd February 18, and others, the Von Leiben &Riesz r peaterd1sclosed in Patent No. 1,038,910, dated September 17,1912, etc. By vacuum discharge is meant current discharge between elec*trodes in space from which nearly all atmosphere is exhausted. Theexpression vacuum discharge repeaters is intended to 1nclude-repeatersof the thermionic types-and also those in which current flows betweenelectrodes in space maintained in a conductive state by the arc orotherwise. The mercury arc repeaterof an earlier application of thisapplicant, Serial No. 709,445,

filed July 13, 1912, is an example of the class of vacuum dischargerepeaters but 1t is not of the thermionic type.

and especially in submarine and wireless telegraph circuits. It isparticularly desirable to exclude transformers from circuits in which anexact reproduction of Wave form is necessary for legibility, as, forexample, in submarine cable circuits. It is also desirable toexcludetransformers from circuits in which undistorted amplification must besecured over a wide range of frequencies, as, for example, in thereproduction of speech and music. "Heretoforeit has been necessary toemploy transformers in circuit with the audion in order to secureeflicient amplification of current by the audion, and this is especiallytrue where the amplification is desired in circuits of-low impedance.This is due to the fact that the impedance of the input circuit of anefiiciently operating audion is very high, at least 100,000 ohms and ingeneral as high as 10 megohms. Hence. in a rent amplification by theaudion is lost. For example, if the impedance of the input circuit ofthe audion is only 100,000 ohms and 1000 ohms impedance, at least 90% ofthe possible currentiamplification is'lost. Moreover, in the case ofaudions ofthe prior art,

the impedance in the output circuit of the audion is always so greatthat a considerable additional loss 7 of possible amplification mustoccur if the output circuit of the audion is directly connected to acircuit of low impedance.

It has been discovered thataudions of the usual type may be soconstructed that, with-' out the use of transformers, they will step upthe input voltage of either direct current 85 7' or alternating currentof any frequency in one step to asmuch as 30 times its original .valueorin two successive steps to as much as 500 times its original value.The voltage amplification thus secured is entirely free from wavedistortion whatever may-be the initial frequency and wave form. Thistypeof audion will, for convenience, be.

hereinafter referred to as the high-voltage output audion. r

It has furthermore been discovered that" audions may beconstructedkwhich will step down the input, voltage, for example, toone- 65 circuit of low impedancerif no transformer is used, the larger'part of the possible curpreferably audions.

third of its original value.- This last mentioned type of audion has ahigh current and a low voltage output; 3 eca use of its low outputimpedance, suchtype of audion can be worked efliciently into a line oflike impedaiicc. This new type of audion will,

' herewith.

It has been discovered that a combination of one or more of theaforementioned highvoltage output type of audions working into one ofthe high-current output type, will operate,.without transformers, from aline of low impedance, for example, 250 ohms, into 'a like line with aresultant current much greater, fifty or more times greater, than wouldflow in the second circuit if it were directly connected to'thefirst'circuit. The present invention-is directed to such combination oftwo difierent types of repeaters, A system designed to secure the sameresult and employing a large number of the high-voltage output type ofaudions connected in multiple and working into a common output circuitin lieu of a single .audion of the high-current output type, forms thesubject-matter of still another application for patent in my name, Ser.No. 841,569 filed ofeven date herewith. The ,present invention may bemore readily understood by reference to the accompanying drawings inwhich Figure 1 is a view in perspective of an audion of the high-voltageoutput type; Fig. 2 is a similar fragmentary View of an audion of thehigh-current output type; Fig. 3' is a similar fragmentary view of thetwo different types of audions embodied in a unitary structure; Fig.4shows a circuit arrangement embodying this invention in which apluralityof audions of thehighvoltage. type in tandem work into'an audion of thelow-voltage type; Fig. 5' shows a simplified circuit arrangement givingthe same-result as in Fig. 4:; Fig. 6 shows a still further modificationmore particularly applicable to telephone circuits} Fig. 7 .shows aplurality of audions of the high-voltage type in tandem working into aplurality of audions of the high current output type, each of the latterfeeding'into a separate output line; and Fig. 8 shows a circuitarrangement embodying theinvention in which the two different types ofaudions are combined in one bulb.

Like reference characters refer to like parts throughout the severalviews,

In the drawings, the audions 1 are of the high-voltage output type andthe audions 2 are of the high-current output type. In the former type,the input electrode may be in the form of a grid. preferably made ofvery fine wire with a line mesh or the like, and the output anode orplate 4: is placed at a considerable distance from the cathode which ispreferably a filament 5, as shown. The filament need not present a largeactive area. The filament, grid and plate are as usual sealed in anevacuated bulb 6. In order to secure best results in this type ofaudion, the grid should be near the filament, the plate should bedistant from the filament, and the grid should present a finely meshedor discontinuous surface between the filament and the plate.

In the hi gh-current output type of audion, the input electrode or grid7 may be at any side of the filament and should have a coarse mesh orpreferably consist merely of a short length of wire. The outputelectrode or plate 8 is placed as near to the filament 9 as isconveniently possible. The filament preferably presents a large, activearea. The filament, grid and plate are as usual sealed in an evacuatedbulb 10. In order to secure the ,best results in this type of audion,the grid and plate should both be near the filament, the filament areashould be large, and'the grid should present the least possibleobstruction between the filament and plate.

As hereinbefore stated, the high-voltage output type of audion gives anamplification with low current and high voltage in its output circuit;whereas the high-current output type gives amplification with highcurrent and low voltage, and hence low impedance, in its output circuit.

In Fig. 4, two high-voltage output audions 1, 1 connected in tandem areshown working into a high-current output audion 2. The batteries 11 arepreferably of such value as to make each of the grids 3, 3 and 7normally about five volts negative with respect to its adjacentfilament. The several filaments are heated by the respective bat teries12. The output circuit of each audion includes its plate, a highresistance 14, a battery 13 and the filament of the audion. Theresistance 14 should be, for example, 100,000 ohms or more. Theinputcircuit of the first audion of the group is directly connected to theinput line 15. The input voltage ,onthe grid of the first audion 1causes an increase in the voltage of the current flowing in the outputcircuit of said audion,

thereby developing a voltage change on the grid of the next audion ofthe series, and so on. As aresult of such construction and arrangementofthese audions, the voltage in the input circuit of the secondof the twoI masses audions in tandem is much greater than that impressed upon thefirst, although the current in the interconnecting circuit is small. Theaudion 2 acts as an amplifier in which the current is increased and thevoltage lowered in its output circuit. Because of the fact that theimpedance in the output circuit of the audion 2 is lowered, it can beworked efiiciently into a line 16 of low impedance. It has been found,for example, that the amplifying means shown in- Fig. 4 will work froman incoming line of 250 ohms impedance into an outgoing line of likeimpedance with a resultant current of more than fifty times that whichwould flow in the outgoing'line if the latter were di rectly connectedto the incoming line.

Fig. 5 shows a simplification of the system illustrated in Fig. 4, inthat a common battery 12 furnishes current to all the filaments, saidfilaments being connected in series with the battery, and a commonbattery 13 serves for all of the plates.-

' Fig. 6 shows a further simplification of thesystem illustrated in Fig.5. An impedance coil 17' is included in bridge of the output circuit ofeach audion, and in the output circuit of the two audions 1, 1,condensers 18, 18 are inserted in series with the resistances 14. Bysuch arrangement the several batteries 11 may be largely reduced .involtage. This arrangement is particularly applicable to embodiment in atelephone system.

Fig. 7' shows a plurality of the high-voltage output audions in tandemworking into a plurality of the high-current output audions, each of thelatter working into its own output circuit 19, 20 or 21. Otherwise, the

circuit arrangement is substantially that shown in Fig. 5. Thearrangement shown in Fig. 7 is particularly applicable to the operationof several loud speaking receivers from a common talking circuit.

Fig. 8 shows a structure and circuit arrangement in which an audion ofthe highvoltage output type works into an audion of the high-currentoutput type, the two audions being contained in a single bulb andoperating from a common filament having one branch 5 for the audion 1and another branch 9 for the audion 2. .The input electrode 7 of theaudion 2 is shown in the form of a short length of wire. The circuitarrangement is substantially that illustrated in Figs. 4 and 5, andfurther description thereof is deemed unnecessary. This structure andairangementhave been found tooperate successfully, without the interosition oftransformers, between lines o the impedance of ordinarytelephone lines.

As applied to submarine cable work for amplifying the feeble currentat'the receiving end the invention is of special imporsired. In generalin the art of submarine,

land and wireless telegraphy, the invention is of importance withreference to recording, high-speed working and direct repetition fromone type of system to another type of system.

What is claimed is:

1. The combination with a source of feeble electric currents, of athermionic repeateryhaving an input circuit directly connected to saidsource of current and an output circuit of high voltage, and a secondthermionic repeater having an output circuit of low impedance and havingan input circuit directly connected to the output circuit of said firstmentioned repeater.

2. The combination with a plurality of thermionic repeaters connected intandem, the first repeater of the series having a, highvoltage outputand the last repeater of the series having a high-current output.

3. The combination with an incoming and an outgoing line of lowimpedance, of a outgoing line.

4. The combination with a line of low impedance, of a current amplif ingmeans directly connected therewith, said amplifying means comprising aplurality of thermionic repeaters in tandem, the first ofsaid repeatershaving a high-voltage output and the last of said repeaters having ahlgh-current output.

5. The combination with a repeater, of a plurality of vacuum dischargerepeaters connected in multiple with the output circuit of said firstmentioned repeater, said mentioned repeater having a high-voltage ageoutput and said other repeaters each having a high-current output.

6. The combination with a thermionic repeater, of a plurality ofthermionic repeaters connected in multiple into which said firstmentioned repeater works, said first mentioned repeater havingahigh-voltage output and said other repeaters having a In witnesswhereof, I hereunto subscribe high-current output. my name this 25 dayof May, A. D. 1914.

7. The combination of two thermionic repeater structures connected intandem and HAROLD DE FOREST ARNOLD 5 having a common inclosing bulb, thefirst of Witnesses:

said structures having a high-vo1tage out- E. EDLER,

put and. the other a high-current output. K. L. STAHL.

